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Comparing of SMB performance of using RDM and VMDK on ESXI 5.0

Testing environment :

Dell Optilex 990 + VMWare ESXi 5.0 U2 + single local 500GB SATA 7200rpm disk for data testing

Client : Windows 7×64 with 6GB RAM

Case 1 : provision of a single SATA 500GB disk using physical RDM, write and read a 8GB video file

write : ~53MB/s – 55MB/s

read : ~62.5MB/s – 66MB/s

write and read a 4GB video file

write : ~70MB/s, read : ~62MB/s – 63MB/s

Case 2 : The SATA 500GB disk is formatted with VMFS (lazy zeroed) and a single 500GB VMDK is attached, write and read a 8GB video file

write : ~27MB/s – 32MB/s (initial) ~50MB/s after several delete and  re-write

read : ~54MB/s – 56MB/s

Case 3 : The SATA 500GB disk is formatted with VMFS (eager zeroed) and a single 500GB VMDK is attached, write and read a 8GB video file

write : ~48MB/s – 52MB/s

read : ~59MB/s – 66MB/s

write and read a 4GB video file

write : ~66MB/s, read : ~~50MB/s – 53MB/s

Case 4 : The SATA 500GB disk is formatted with VMFS (thin provision) and a single 500GB VMDK is attached, write and read a 8GB video file

write : ~26MB/s (initial), ~50MB/s after several delete and  re-write

read : ~47MB/s – 50MB/s

http://www.vmware.com/pdf/Perf_Best_Practices_vSphere5.0.pdf

See this as well : http://www.ntpro.nl/blog/archives/2241-Mythbusting-Disk-provisioning-type-doesnt-affect-performance.html

Testing Using PowerEdge R720XD with ESXI 5.1U1

Client : Windows 7×64 with 16GB RAM

Case 1 : Provision of a local RAID 5 VD forming using 4x500GB SATA disk using eager zero thin provision

Sequential write speed : ~62MB/S – ~63MB/s for a 265GB of data set

Case 2 : Provision of a local RAID 5 VD forming using 4x500GB SATA disk using rdm

sequential write speed : ~67MB/s – ~70MB/s fr a 265GB of data set

Conclusion : In my environment, which the data disk is provisioned by a local RAID Controller on the same server, rdm still provide a little bit more performance than using VMDK (~5% to 8%), in contrast to the references provided by the net (which the comparisons are usually done on robust NAS/SAN storage)

More Reference : http://blogs.vmware.com/vsphere/2013/01/vsphere-5-1-vmdk-versus-rdm.html

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